Properly create container on node update
This merge request fixes a bug in container creation in a certain case: When adding the pagedesigner field to an existing content types with nodes/content, resaving the nodes didn't add the entity reference to the newly created container. This corrupted the data structure and caused issues on copying pagedesigner content.
The changes set the entity loopback from the container already on update, if the entity is already saved / not new.
Edited by Philippe von Bergen